In the healthcare industry, the routine complete blood count (CBC) is a common test. Typically, a blood sample is run through an automated blood analyzer configured to count a large number of red cells (erythrocytes, RBC's), white cells (leukocytes, WBC's), and platelets (thrombocytes). In general, the automated blood analyzer provides an accurate volumetric count of each, along with varying amounts of information regarding the morphology of the counted cells. Based on the analysis, some samples are chosen for manual examination. For example, the manual differential blood count examination (i.e., “manual diff”) includes smearing, drying, and staining the blood onto a glass slide. This slide prep is often performed by automated equipment, but is also performed manually, especially in smaller labs. The slide is then examined by a technician or physician (the reviewer) under a microscope using up to 100× magnification oil immersion optics. The examination typically requires the reviewer to count and classify 100 WBC's, examine the shape and color and measure the diameter of RBC's, and make an estimate of the platelet and WBC count per unit area, for example. The data from such a manual examination is usually presented to the clinician with data obtained from an automated blood analyzer and is known as a CBC result, or “CBC with manual diff”.
Due to the speed and efficiency of automated blood analyzers, a large portion of the cost of all CBC's is incurred in the labor cost of that subset of samples examined manually. For example, a group of technicians can process between 40 and 70 samples in one eight hour shift. For various reasons (e.g., required training, ergonomic issues and nature of the work), however, in many markets it is difficult to hire skilled technicians. Accordingly, hospital and lab human resource managers generally find it difficult to adequately support the staffing required for extended hours of operation (e.g., 2nd and 3rd shifts).
Some microscope manufacturers have introduced automated systems for creating a digital image of a slide-mounted sample at some magnification. In general, these tools cover a range of research and clinical applications in medicine, and are configured with different optical, slide handling, camera, and image processing sub-systems depending upon the application. However, the subset of prior art systems that can deliver the optical requirements for hematology generally do not meet the minimum requirements for automation and throughput required in a modern clinical laboratory.